There are many occurrences wherein it is desirable to optically couple two or more optical fibers to each other. For example. In optical amplification, a signal fiber carries a signal and is optically pumped using laser light having another wavelength to amplify the signal. To that effect, the laser light coming from the pump fibers is carried into the signal fiber and thereby provides the power required to amplify the signal circulating in, the signal fiber.
Many techniques are available for optically coupling optical fibers to each other in this manner. For example, in one such technique, the optical fibers are stripped of their sheath and heated while positioned substantially adjacent to each other until the pump fibers are fused and optically coupled to the signal fiber. This involves deforming the pump fibers until they achieve a shape suitable for optically coupling to the signal fiber.
However, coupling the pump fiber typically occurs by deforming to a relatively large extend the pump fiber around the periphery of the cladding of the signal fiber. This creates surface tension problems that result in power losses. Since it is desirable, in many instances, to pump relatively large power into the signal fiber, these power losses may heat the optical fibers and eventually lead to failure of the optical amplifier. In addition, these methods for manufacturing optical amplifiers and other devices in which optical fibers are optically coupled to each other are relatively difficult to perform and it is relatively difficult to achieve reproducible results using these methods.
Another manner of optically coupling pump fibers to a signal fiber involves the use of a signal fiber having a relatively large diameter. Then, the pumped fibers may be axially coupled to the cladding of the signal fiber which is then deformed to achieve a shape suitable for guiding the light carried by the pump fibers into the core of the signal fiber. Once again, these methods for manufacturing optical fibers are relatively complex to implement. Also, they may lead to the creation of stresses within the coupled assemblies, as there is typically a need to handle the optical fibers and attach them to supports for packaging purposes.
Against this background, there exists a need in the industry to provide an improved methods and devices for optically coupling optical fibers. An object of the present invention is therefore to provide such methods and devices for optically coupling optical fibers.